1. Field of the Invention
This invention relates to antibodies to anthrax, and, in particular, to Bacillus species-specific antibodies that bind to the EA1 antigen of the S-layer, and to methods for making and using these antibodies. The invention further relates to kits that contain Bacillus species-specific antibodies for the rapid detection and identification of individual Bacillus species. The invention further relates to isolated EA1 antigen and compositions that contain the EA1 antigen for use as pharmaceuticals.
2. Description of the Background
Anthrax is a world wide disease of sheep, cattle, horses and other mammals caused by the spore-forming, saprophytic bacterium, Bacillus anthracis. Soil, the most common location of anthrax spores, typically becomes contaminated from the carcasses of infected animals that have died. Spores from the decaying carcasses are deposited in the soil, in the water and on vegetation. Like most types of spores, anthrax spores are very resistant to environmental changes such as extremes of heat and cold, and severe desiccation. Consequently, undisturbed spores can remain viable for decades.
Infection usually begins by entry of spores through injured skin or mucous membranes. Spores germinate at the site of entry and proliferate. Although not generally considered a respiratory pathogen, anthrax spores can initiate infection through the lungs. For example, Woolsorter's Disease, a rare from of anthrax, is caused by the inhalation of large quantities of anthrax spores from the dust of wool, hair or hides. Deep, concentrated inhalation results in the germination of spores in lung tissue and tracheobronchial lymph nodes. Unchecked, this disease is almost always fatal with symptoms which include the production of hemorrhagic mediastinitis, pneumonia, meningitis and sepsis. In anthrax sepsis, the number of organisms in the blood can exceed ten million per milliliter prior to death.
Most animals are susceptible to anthrax, but resistance is not uncommon (e.g. rat). In resistant animals, organisms proliferate for a few hours while also generating a massive accumulation of leukocytes. In these animals, dying organisms remain confined to capsules which gradually disintegrate and disappear. In susceptible animals, organisms germinate and rapidly proliferate at the site of entry. The most common portal of entry in animals is the mouth and the gastrointestinal tract. Spores within contaminated soil find easy access when ingested with spiny or other irritating vegetation. In humans, scratches of the skin and other injuries are the most likely routes of infection. Germination and growth of the vegetative organisms results in formation of a gelatinous edema and congestion with a generation of large amounts of proteinaceous fluid containing leukocytes. Bacilli spread via lymphatics to the bloodstream and multiply freely in blood and tissues shortly before death of the animal. In the plasma of animals dying from anthrax, a toxic factor has been identified. This factor kills mice upon inoculation and is specifically neutralized by anthrax antiserum.
Two factors are believed to be responsible for the toxic effect of anthrax infection; an edematogenic factor (EF) and a lethal factor (LF). These in combination with a membrane binding factor or protective antigen (PA), may have the capacity to confer active protection against disease (PNAS 79:3162-66, 1982). The genes which encode these protein factors (pag for PA, cya for EF, and lef for LF) have been cloned and sequenced (se Gene 69:287-300, 1988; Gene 71:293-98, 1988; and Gene 81:45-54, 1989). A recombinant strain of B. anthracis has been produced which is unable to produce LF or EF (U.S. Pat. No. 5,840,312). This strain has been used to create immunogenic compositions against anthrax infection.
Active immunity to anthrax can be induced in susceptible animals by vaccination with live attenuated bacilli, with spore suspensions, or with protective antigens from culture filtrates. Immunity is often incomplete and not long lasting so that the preferred treatment of choice is a course of antibiotics. If started early, antibiotic therapy has a high success rate.
As an acute, febrile disease of virtually all warm-blooded animals, including man, anthrax has been used in biological weapons. Terrorists have included dry spores in letters to target specific individuals for harassment. Biological weapons of mass destruction have been developed that contain large quantities of anthrax spores for release over enemy territory. Once released, spores contaminate a wide geographical area, infecting nearly all susceptible mammals. Due to the spore's resistance to heat and dry conditions, contaminated land can remain a danger for years. In view of the serious threat posed by the disease, effective diagnostic tools are needed to assist in prevention and control of natural and man-made outbreaks.